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Pressure
Gradient Force |
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Coriolis
Force |
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Surface
Friction |
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Geostrophic Balance |
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Thermal
Wind Balance |
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Scales
of Motion |
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Pressure
gradient force |
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Coriolis
force |
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Friction |
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Centrifugal force |
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PG =
(pressure difference) / distance |
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Pressure gradient force force goes from high
pressure to low pressure. |
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Closely
spaced isobars on a weather map indicate steep pressure gradient. |
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Coriolis
force causes thw wind to deflect to the right of its intent path in the
Northern Hemisphere and to the left in the Southern Hemisphere. |
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The magnitude of Coriolis force depends on (1)
the rotation of the Earth, (2) the speed of the moving object, and (3) its latitudinal location. |
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The stronger the speed (such as wind speed), the
stronger the Coriolis force. |
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The higher the latitude, the stronger the
Coriolis force. |
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The Corioils force is zero at the equator. |
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Coriolis force is one major factor that
determine weather pattern. |
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Friction
Force = c * V |
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c =
friction coefficient |
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V =
wind speed |
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The
force that change the direction (but not the speed) of motion is called the
centrifugal force. |
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Centrifugal Force = V2 / R. |
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V =
wind speed |
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R =
the radius of the curvature |
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For high
pressure system |
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gradient wind > geostrophic wind |
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supergeostropic. |
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For low
pressure system |
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gradient wind < geostrophic wind |
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subgeostropic. |
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¶U/¶z µ ¶T/¶y |
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The
vertical shear of zonal wind is related to the latitudinal gradient of
temperature. |
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Jet
streams usually are formed above baroclinic zone (such as the polar front). |
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The hurricane is characterized by a strong
thermally direct circulation with the rising of warm air near the center of
the storm and the sinking of cooler air outside. |
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Notes